EP1198778B1 - Declencheur de numeriseur optique mains libres - Google Patents

Declencheur de numeriseur optique mains libres Download PDF

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Publication number
EP1198778B1
EP1198778B1 EP00921892A EP00921892A EP1198778B1 EP 1198778 B1 EP1198778 B1 EP 1198778B1 EP 00921892 A EP00921892 A EP 00921892A EP 00921892 A EP00921892 A EP 00921892A EP 1198778 B1 EP1198778 B1 EP 1198778B1
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EP
European Patent Office
Prior art keywords
time
detecting
optical scanner
scanner
signal
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EP00921892A
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German (de)
English (en)
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EP1198778A1 (fr
EP1198778A4 (fr
Inventor
Brian M. Kelly
Brian B. Wood
Bruce W. Dozier
David P. Ingles
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Datalogic Scanning Inc
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PSC Scanning Inc
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    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
    • G06K7/00—Methods or arrangements for sensing record carriers, e.g. for reading patterns
    • G06K7/10—Methods or arrangements for sensing record carriers, e.g. for reading patterns by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation
    • G06K7/10544—Methods or arrangements for sensing record carriers, e.g. for reading patterns by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation by scanning of the records by radiation in the optical part of the electromagnetic spectrum
    • G06K7/10821—Methods or arrangements for sensing record carriers, e.g. for reading patterns by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation by scanning of the records by radiation in the optical part of the electromagnetic spectrum further details of bar or optical code scanning devices
    • G06K7/10851—Circuits for pulse shaping, amplifying, eliminating noise signals, checking the function of the sensing device
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
    • G06K2207/00—Other aspects
    • G06K2207/1012—Special detection of object

Definitions

  • the field of the present invention relates to data reading systems.
  • a method and apparatus are described herein for detecting objects with an optical reading unit, such as a bar code scanner.
  • stationary, handheld, or combination stationary/handheld, data reading devices are useful for reading a wide array of indicia found on consumer and industrial products, such as traditional linear or one-dimensional bar codes, two-dimensional symbologies, matrix array symbols, patterns and logos, signatures, and other images.
  • Information encoded in any number of different encoded formats may then be used for numerous applications including retail check-out, inventory management, material handling, manufacturing, and package sortation and transportation.
  • Current data readers may incorporate techniques for automatically detecting an object and initiating and terminating scanning and decoding operations. For example, a clerk at a check-out line using a handheld scanner that incorporates today's automatic reading techniques now has the option of mounting the scanner in a stand, which advantageously provides hands-free operation, or manually actuating the trigger to begin the data acquisition process.
  • the present inventors have recognized the need for an improved system for detecting objects with an optical reader that is real-time responsive to random noise within a scanner's circuitry, accommodates varying degrees of reflectivity of target materials, and requires neither additional circuitry nor reflective tape to accurately detect an object.
  • An optical information reading method and device is disclosed in US 5,426,288, which prevents the generation of erroneous reading by specifying a reliable reading range for a bar code or like information.
  • a microcomputer calculates the distance between the position of reflection of laser light from the bar code and a position at which the same laser light enters the scanning unit based on a time difference between the emission of the laser light and the reception of the reflected laser light.
  • an automatic electronically triggered scanner which includes photo sensing apparatus for reading bar code data and then ascertaining whether the bar code data is valid. Further, following the reading and decoding of a valid bar code, the further decoding of bar code data by the scanner is inhibited until a predetermined condition is met to ensure that the bar code just read (which provided valid data) is not re-read.
  • the preferred embodiments relate to a system and method for detecting an object within the field of view of an optical reader, such as bar code scanner.
  • Object detection is determined by a software algorithm that may be embedded in a hardware component of the scanner, such as a controller or microprocessor.
  • the object detection software algorithm uses a current trigger threshold to determine whether there is a change in the amount of reflected light energy sufficient to indicate the presence of motion in the scanner field of view.
  • a current trigger threshold is set by pulsing a laser diode, generating a signal of returned light energy, sampling the signal until a transition in the signal occurs, and measuring the amount of time from when the pulse stopped to when the transition occurred.
  • the count value of the current trigger threshold is then preferably deviated by a configurable amount to obtain a current trigger threshold range.
  • a current sample average may then be compared to the current trigger threshold range in order to detect a trigger condition and enable the system for scanning and decoding.
  • a scanner operating in accordance with the above-described method may include a scan engine having a light source capable of being modulated, an optical interface for receiving information, and a processor for conditioning the received information and determining whether an object is detected.
  • the effective range of a scanner utilizing the above-described method is increased as a scan event will be triggered based on a relatively small time change.
  • the above-described method normalizes random noise within a scanner without additional circuitry or reflective tape.
  • Various other embodiments may utilize some but not all of the above elements, or may include additional refinements, while obtaining the benefit of accurate object detection.
  • Fig. I shows four basic blocks of a simplified optical reader useful in illustrating certain aspects of preferred embodiments.
  • Fig. 1 illustrates a scan engine block 102, a control and decode engine block 104, a host interface block 106, and a power supply block 108.
  • the following discussion focuses on the scan engine block 102 and the control and engine decode engine block 104 that are particularly pertinent to a method and apparatus according to preferred embodiments for detecting objects with an optical reading unit, such as a bar code scanner.
  • the scan engine block 102 typically includes an illumination source for illuminating a target or object
  • the control and engine decode block 104 typically includes a photosensor for collecting the refracted and/or reflected light from the target, a signal processor for conditioning the received information, and a decoder.
  • the artificial illumination source may comprise, for example, a laser diode, an array of light-emitting diodes (LEDs), an incandescent light, or any other suitable light source.
  • the photosensor may comprise, for example, a photo detector diode, a solid-state image sensor such as a charge-coupled device (CCD) linear sensor, a two-dimensional CCD array, or a linear or multi-dimcnsional CMOS array (such as described in copending U.S. Patent 6 155 488, Serial No. 08/697,408 filed August 23, 1996), or any other suitable detecting device.
  • the signal processor may comprise, for example, an analog signal processor and a digitizer or other suitable processor for conditioning the received information.
  • a microcontroller may optionally be in communication with the signal processor and the decoder for receiving and further processing the received information or data.
  • Fig. 2 shows a more detailed block diagram including pertinent components of an optical reader illustrative of certain aspects of preferred embodiments.
  • the optical reader may include an artificial illumination source 202, a photosensor 204, a controller 206, a signal conditioning and processing block 208, a memory buffer 210 (e.g., a first-in first-out (FIFO) memory 212), a memory 214, a decoder 216, and an input/output (I/O) interface 218.
  • the optical reader may be configured so as to read and recognize information in more than one data format. Such an optical reader is disclosed in U.S. Patent 6 176 429, Serial No. 09/118,228, filed July 17, 1998.
  • the artificial illumination source 202 is activated so as to illuminate a target 220 to be read.
  • Light reflected from the target 220 is detected by the photosensor 204, which outputs a signal 222 indicative of lighter and darker portions of the target 220.
  • the photosensor output signal 222 is fed to the signal conditioning and processing block 208, which conditions it and identifies the portions of the signal 222 corresponding to the relatively lighter and darker portions of the target 220.
  • the signal conditioning and processing block 208 can have operating parameters which are dynamically selected by the controller 206.
  • the signal conditioning and processing block 208 outputs data indicative of the relative light and dark portions of the target 220, and this data is stored by the controller 206 in the FIFO 212 for further processing.
  • the decoder 216 reads data from the FIFO 212 and processes the data to determine whether the data can be recognized.
  • the decoder 216 may operate according to a program stored in the memory 210.
  • the memory 210 may comprise, for example, a flash programmable read-only memory (PROM), and may also comprise a static random-access memory (RAM) which can be used as a scratchpad area.
  • the decoder 216 outputs data across the I/O interface 218 to a host computer or some other system which utilizes the decoded information.
  • the decoder 216 need not be resident in the same device as the other components shown in Fig. 2, but may alternatively be located with a host system.
  • the system detects an object within the field of view of an optical reader, such as bar code scanner 300.
  • Scanner 300 may be constructed of a lightweight plastic housing having a head portion 302 and pistol-grip type handle portion 304.
  • the head portion 302 may contain a removable scan module or assembly that contains an optical and electrical assembly.
  • the optical and electrical assembly may include a printed circuit board 306, a collection mirror 308, a laser diode assembly including a laser diode 310, a photodetector and scanning motor assembly 312, and a beam deflector in the form of an oscillating or dithering mirror 314.
  • the laser diode 310 produces a light beam which projects along a first path 316 to a first scanning mechanism or facet 318.
  • the facet 318 may be tilted upwardly so as to project the beam along a second path 320 to the mirror 312.
  • the mirror 312 may be tilted slightly downwardly to project the outgoing beam along a third path 322 through the window 324 towards the object to be detected and a data symbol, if there is one, to be decoded.
  • the system according to preferred embodiments is particularly well-suited for use with a handheld scanner such as scanner 300 shown in Fig. 3 and disclosed in U.S. Patent No. 5,260,554.
  • the scanner 300 shown in Fig. 3 is for illustration purposes only and must not be thought to limit the type of scanner that may utilize any of the preferred embodiments.
  • the system may be utilized with a fixed scanner (such as the fixed scanners disclosed in U.S. Patent 6,047,889 filed June 7, 1996 ), or utilized with a handheld scanner, or any combination thereof (such as handheld scanner 300 illustrated in Fig. 3 that can be mounted on a stand).
  • object detection is determined by a software algorithm that may be embedded in a hardware component of a scanner's circuitry, such as microprocessor or controller 206 shown in Fig. 2.
  • a software algorithm that may be embedded in a hardware component of a scanner's circuitry, such as microprocessor or controller 206 shown in Fig. 2.
  • An example of a microprocessor that could be modified to include a software algorithm according to certain aspects of the preferred embodiments is disclosed in U.S. Patent No. 5,237,161 and illustrated in Fig. 14 thereof.
  • the object detection software algorithm uses a current trigger threshold to determine whether there is a change in the amount of reflected light energy sufficient to indicate the presence of motion in the scanner field of view.
  • a microcontroller such as controller 206 illustrated in Fig. 2, energizes scan engine 102 via a MODULE_EN signal 112, which remains energized until power is removed from the scanner.
  • a BRAKE_EN signal 110 is set active which energizes a mirror brake (such as the braking mechanism disclosed in U.S. Patent 6,547,145 filed September 14, 1998, and U.S. Patent 6,152,372, Serial No. 08/934,487, filed June 19, 1997) which holds the scan engine's mirror (such as mirror 314 shown in Fig. 3) in a relatively fixed or neutral position.
  • the laser diode for example diode 310, is modulated using a LASER-EN signal 116 preferably at a rate of 1 milliseconds (mS) once every 25mS. This modulation produces a dim but visible point of light that can be detected on objects located in the beam line.
  • the light reflected off of the object 220 is collected by the scan engine optical system 102 and converted to an electrical signal 222 preferably by an optically band limited photo detector, such as photosensor 204.
  • this electrical signal 222 (cf. Fig.2) consists of a pulse having an amplitude and rise time that is a function of the reflected light energy from the object 220 and the distance of the object 220 from the laser light source 202.
  • the return signal 222 generated by the photosensor or photodiode 204 is preferably amplified at amplifier 402 and clamped to a fixed voltage level (VREF) 404.
  • This amplified signal 406 is then applied to a circuit, such as circuit 408, that uses a comparator 410 to compare the amplified signal 406 to the same fixed reference voltage 404.
  • the circuit 408 is preferably configured as a zero crossing detector that has an output which will be a logic zero when the input signal polarity is positive with respect to the fixed reference 404 and a logic one when the input signal is negative with respect to the same reference voltage 404.
  • This conditioned, binary or digitized signal is illustrated as OBS-BAR signal 114 in Figs. 1 and 4-8.
  • a time relationship exists between the extinguishing laser diode 310 via LASER_EN 116 and the point at which the reflected pulse energy level decays below the fixed reference level 404, indicated by a positive transition of OBS_BAR signal 114.
  • This period varies as the reflected optical power from the object 220 varies, as respectively illustrated in Figs. 5-7 with a white paper target at 2.54 - 7.62 cm (1-3 inch) or 15.24 cm (6 inch), or 40.34 cm (16 inch) and greater, and the corresponding change in time or time delta ( ⁇ ) of 1.1mS, 1.6mS, and 2.2mS, respectively.
  • the surface properties of the object or target 220 is an integral part of the relationship of signals 114, 116. If the target surface, based on its color, texture, etc., exhibits a low reflectivity, the corresponding power change throughout the depth of field of the scan engine is small, which produces a small time deviation (typically a ⁇ of 200 microseconds ( ⁇ S) from far field to near field) in the signals' 114, 116 relationship. Another factor that affects this relationship is variability of the scan engines themselves. The scan engine variability manifests itself as an increase or decrease of overall dynamic range of the time delta ⁇ .
  • the overall dynamic range of the signal can vary from 1.5mS to 900 ⁇ S from far field to near field for different scan engines. It is noted, however, that such parameters of the time relationship may only be valid during the period and under the conditions described above. Other factors, such as temperature, may affect the dynamic range of this timing relationship of signals 114, 116. As the scan engine is heated or cooled, the efficiency of the photo detector and associated circuitry may vary, increasing or decreasing the overall dynamic range of the timing relationship.
  • a fixed time limit or fixed trigger threshold fails to vary in accordance with the overall dynamic range of the above-described time relationship, causing trigger sensitivity problems that lead to ineffective or inaccurate object detection.
  • the object detection software algorithm according to preferred embodiments disclosed herein does not rely on a fixed threshold. On the contrary, the preferred embodiments produce a trigger event based on a current trigger threshold determined by input from the received signal, such as OBS_BAR signal 114.
  • the object detection software algorithm may advantageously normalize scan engine variations resulting from process and temperature variations.
  • the effective range of the scanner may be increased as a scan cycle or scan event will be triggered based on a relatively small time change, shown in Fig. 8 as time range ⁇ , which may be a configurable deviation from the current OBS-BAR position 150 preferably determined by the time relationship of a plurality of current received signals.
  • the object detection software 500 begins with the step of "begin” 502 and then the step of “stop the motor and set the brake” 504.
  • the microcontroller or microprocessor such as controller 206, may perform this step 504 by asserting the MODULE_EN signal 112 and BRAKE_EN signal 110 continuously.
  • the background of the scanner's field of view is then determined at the step of "collect 16(N) OBS_BAR positions average to set background” 506.
  • Data on the current OBS_BAR position 150 is collected via a data collection routine such as the one shown in Fig. 9b.
  • a preferred embodiment of the data collection routine involves pulsing or modulating the light source for a predetermined length of time. Pulsing the light source is preferably effected by asserting the LASER_EN signal 116 for 1mS every 25mS which produces a laser spot on the target, as shown in steps “delay for 25mS” 552, “set laser on” 554, and "delay for 1mS” 556.
  • the OBS_BAR line 114 is sampled by the controller 206. Sampling is preferably done every 20 ⁇ S at the step “delay 20uS” 564 until a transition, such as transition 115, occurs in the OBS_BAR signal 114 at the step of "has OBS_BAR transition” 560.
  • a transition such as transition 115
  • positive transition 115 is a zero crossing of the amplified photodetector signal 406 as it decays below the fixed reference voltage level 404.
  • a transition indicates a change in reflected light energy.
  • step 9b if no transition is detected within the configurable time frame of 20 ⁇ S, the time of such a resolution sample loop is stored in memory at step “increment time” 516 and the step “has OBS_BAR transition” 560 is repeated.
  • the total amount of time or total number of resolution sample loops are added together and saved at the step of "save current count” 566.
  • the data collection routine ends at step “end” 568.
  • the data collection routine may be performed a number of times in order to determine the background of the scanner's field of view. As shown in Fig. 9a at the step of "collect 16(N) OBS_BAR positions average to set background" 506, the data collection routine has been performed sixteen times wherein sixteen different count values are stored in memory, such as memory 210 illustrated in Fig. 2, and averaged together to define an average count value of the amount of time it took for sixteen successive transitions in signal 114 to occur.
  • Such an average count value, or current position in time of the OBS-BAR transition is preferably used to set the current trigger threshold or background of the scanner.
  • current OBS_BAR position 150 is illustrated as being between the near field or minimum range 152 (where the maximum power is coming back) and the far field or maximum range 154 (where the least amount of power is coming back) of the scanner. During the acquisition of the first samples or count values used to obtain the current OBS_BAR position 150, no trigger events are permitted.
  • the current trigger threshold is compared to another count sample to determine if a trigger condition is present.
  • a trigger condition is present when the count value of the current trigger threshold or background is different than the count value of a recent current sample. When the change in transition time or the change in count value between the background and the current sample is sufficient to indicate the presence of an object, a valid trigger condition is present.
  • the current sample is preferably an average of a number of successive count values collected via a data collection routine such as the routine shown in Fig. 9b, and most preferably four recent count values averaged together to define a current sample average as illustrated in the step of "collect 4(N) OBS_BAR positions average to set current" 508.
  • the current sample average is then compared to the current trigger threshold or background at step "compare current to background” 510 to determine if the change in transition times is sufficient to indicate a valid trigger condition.
  • a valid trigger condition preferably exists when the magnitude of the difference between the background or current trigger threshold and the current sample is greater than the magnitude of a configurable delta as shown in step "is
  • a valid trigger condition occurs at the step of "valid trigger condition" 514.
  • a valid trigger condition is not present and the process repeats itself at the step of "collect 4(N) OBS_BAR positions average to set current" 508.
  • Fig. 8 illustrates the timing relationship of the configurable delta and the current trigger threshold.
  • the current trigger threshold or OBS_BAR current position 150 is deviated by a configurable amount (preferably +/- 3 counts) to obtain a current trigger threshold range.
  • a current trigger threshold range is shown as range ⁇ in Fig. 8, which is defined by a current lower trigger threshold 156 and a current upper trigger threshold 158.
  • a valid trigger condition exists, such as that occurring in step 512, when the current sample average falls outside the current trigger threshold range ⁇ .
  • a scan event may be triggered.
  • a scan event is triggered and the system is enabled for decoding as shown at the step of "enable the system for decode” 520 and the object detection algorithm ends at step “end” 522. If the desired number of triggers has not been met at step 518, the process repeats itself at the step of "collect 4(N) OBS_BAR positions average to set current" 508.
  • the microcontroller releases the BRAKE_EN signal 110 and fully turns on the laser light source via LASER_EN signal 116.
  • the scanning mechanism (such as dither mirror 312) is then activated producing a scan line and a symbol decoding sequence is initiated.
  • This scan state or scan mode is exited by either of two conditions, namely, a successful decode read or by no decode read occurring within a configurable time period, which is preferably default at 2 seconds.
  • the system Upon exiting the scan mode, the system returns to the object detection mode as shown in Fig.
  • the system may optionally include a wake-up feature for initializing the object detection mode 500 shown in Fig. 9.
  • the scanner advantageously begins its object detection mode 500 of pulsing or modulating a laser diode only after a wake-up event occurs.
  • Fig. 10 shows a passive sensor block 602 designed to reduce operation currents and preserve the life of the scanning components.
  • Fig. 10 shows a lower power thermal mode system including a passive thermal element or pyroelectric element block 602 actuated by thermal energy, such as the thermal energy created by the heat of a clerk's hand as the clerk brings the symbol to be read to within the scanner's field of view.
  • the passive thermal element or pyrotechnic element may be a capacitive switch, such as a capacitive touch switch commonly associated with touch-dimmer lamps.
  • the passive sensor block 602 preferably sends data to a signal processor 604 that processes the thermal energy data and determines whether to release a thermal activation signal 606 to microcontroller 608 which in turn may release a LASER_EN signal 116 and a MODULE_EN signal 112 to scan engine 610 according to certain aspects.
  • a wake-up or object detection initiating algorithm may begin with the step of "scanner in laser sense mode" 620. If the scanner remains inactive over a configurable time limit as shown in step “scanner inactivity timer elapsed” 622, step “lower power thermal detect mode” 624 is initiated until a thermal change is detected at “thermal change detected” 626 and the timer is reset at “reset inactivity timer” 628, wherein the process repeats itself at "scanner in laser sense mode” 620.
  • a label gone or double read function may optionally be added to the end of the object detection function 500 shown in Fig. 9.
  • a logic read algorithm preferably begins with the last step of the object detection step of "enable the system for decode” 530 (shown in Fig. 12 as "Enable the system for decode. Release brake. Turn laser full on. Begin to scan. Initialize scan time out”). Once the brake is released, the laser turned on full, and a scan is begun, the data is read at "read data" 702 and attempted to be decoded at "Is data decodable?" 704.
  • step 502 of the object detection algorithm is repeated. If the data is not decodable and the scan time out period has lapsed at "Scan time out period elapsed?" 706, step 502 of the object detection algorithm is repeated. If not, the "read data" step 702 is repeated.
  • step 502 of the object detection algorithm is repeated.
  • a scanner utilizing a logic decode routine such as that shown in Fig. 12, in conjunction with an object detection technique of a preferred embodiment, may advantageously allow a scanner to automatically detect an object and decode a symbol without continuously decoding the same symbol present in the scan field.

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Abstract

L'invention concerne un procédé et un appareil permettant de détecter un objet dans le champ de vision d'un lecteur optique tel qu'un numériseur de code barre (102). La détection d'objet est déterminée par un algorithme logiciel qui peut être incrusté dans un contrôleur (104) ou microprocesseur intégré dans le numériseur. L'algorithme logiciel de détection d'objet utilise un seuil de déclenchement du courant pour déterminer si la quantité de lumière réfléchie (116), suffisante pour indiquer la présence d'un mouvement dans le champ de vision du numériseur (102), varie. Le système peut normaliser le bruit aléatoire dans un circuit de numériseur et s'adapter à différents degrés de réflexion de matières cibles sans avoir à faire appel à un circuit supplémentaire ou à une bande de réflexion pour détecter avec précision un objet.

Claims (20)

  1. Procédé de détection de la présence d'un objet avec un balayeur optique (300) qui émet une impulsion d'une source de lumière (310) dirigée vers une région où l'objet peut être présent, détecte une réflexion de la lumière fournie par impulsion, et génère en réponse un signal électrique et convertit le signal électrique en un signal de balayage binaire, le signal électrique ayant une amplitude déterminée par l'intensité de la lumière détectée, le procédé étant caractérisé en ce qu'il comprend les étapes suivantes consistant à :
    - mesurer un premier temps en générant une première impulsion de lumière dirigée vers la région, détecter une réflexion résultante de la lumière fournie par impulsion, générer un signal électrique en réponse, convertir le signal électrique en un premier signal binaire et mesurer le temps qui s'écoule de la génération de ladite première impulsion jusqu'à ce qu'une transition dans le premier signal de balayage binaire apparaisse ;
    - mesurer un second temps en générant une seconde impulsion de lumière dirigée vers la région, détecter une réflexion résultante de la lumière fournie par impulsion, générer un signal électrique en réponse, convertir le signal électrique en un second signal binaire et mesurer le temps qui s'écoule de la génération de ladite seconde impulsion jusqu'à ce qu'une transition dans le second signal de balayage binaire apparaisse ; et
    - déterminer si le second temps est différent du premier temps et détecter de ce fait la présence de l'objet dans la région.
  2. Procédé de détection de la présence d'un objet avec un balayeur optique (300) selon la revendication 1, comprenant en outre la déviation du premier temps pour définir une plage de seuil de déclenchement actuelle.
  3. Procédé de détection de la présence d'un objet avec un balayeur optique (300) selon la revendication 1, comprenant en outre la répétition de l'étape consistant à déterminer un premier temps afin d'obtenir un premier temps en moyenne, où le premier temps en moyenne est utilisé pour établir un seuil de déclenchement actuel.
  4. Procédé de détection de la présence d'un objet avec un balayeur optique (300) selon la revendication 3, comprenant en outre la déviation du seuil de déclenchement actuel pour définir une plage de seuil de déclenchement actuelle.
  5. Procédé de détection de la présence d'un objet avec un balayeur optique (300) selon la revendication 4, comprenant en outre la répétition de l'étape consistant à déterminer un second temps afin d'obtenir un second temps en moyenne, où le second temps en moyenne est utilisé pour établir une moyenne d'échantillon actuelle.
  6. Procédé de détection de la présence d'un objet avec un balayeur optique (300) selon la revendication 5, comprenant en outre l'étape consistant à établir une condition de déclenchement quand la moyenne d'échantillon actuelle chute à l'extérieur de la plage de seuil de déclenchement actuelle.
  7. Procédé de détection de la présence d'un objet avec un balayeur optique (300) selon l'une quelconque des revendications 1 à 6, comprenant en outre la détection d'un changement thermique dans le balayeur optique (300) avant d'initier l'étape consistant à déterminer un premier temps.
  8. Procédé de détection de la présence d'un objet avec un balayeur optique (300) selon l'une quelconque des revendications 1 à 7, comprenant en outre l'étape consistant à établir l'existence d'une condition de déclenchement quand le second temps est différent du premier temps, et à fournir une puissance totale à la source de lumière (310) une fois qu'un certain nombre souhaité de conditions de déclenchement a été établi afin d'initier des opérations de balayage.
  9. Procédé de détection de la présence d'un objet avec un balayeur optique (300) la revendication 8, comprenant en outre la lecture et le décodage de données pendant des opérations de balayage, la détection du fait que les mêmes données ont déjà été lues et décodées et la détection du fait que les données ont été retirées avant d'être lues et décodées avec succès.
  10. Procédé de détection de la présence d'un objet avec un balayeur optique (300) selon l'une quelconque des revendications 1 à 9, comprenant en outre l'étape consistant à établir une condition de déclenchement quand l'amplitude de la différence entre le premier temps et le second temps est supérieure à l'amplitude d'un delta configurable.
  11. Procédé de détection de la présence d'un objet avec un balayeur optique (300) selon l'une quelconque des revendications 1 à 10, dans lequel le premier temps et le second temps sont représentés par des premier et second comptes respectifs.
  12. Procédé de détection de la présence d'un objet avec un balayeur optique (300) selon l'une quelconque des revendications 1 à 11, dans lequel le premier temps et le second temps sont des périodes depuis un évènement de référence.
  13. Procédé de détection de la présence d'un objet avec un balayeur optique (300) selon la revendication 12, dans lequel l'évènement de référence est la fin de l'impulsion de la source de lumière (310).
  14. Lecteur optique (300) comprenant une source de lumière (310) pour envoyer une lumière par impulsions, un détecteur pour générer un signal électrique ayant une amplitude déterminée par l'intensité de la lumière renvoyée détectée, et un processeur de conditionnement de signal pour convertir le signal électrique en un signal de balayage binaire dans lequel une transition dans le signal de balayage binaire a lieu à cause d'un changement de la réflectivité de lumière indiquant la détection d'un objet,
    le lecteur optique (300) étant caractérisé en ce qu'il comprend en outre :
    un contrôleur (206) pour mesurer un temps à partir du moment où la lumière est envoyée par impulsion au point auquel a lieu une transition dans le signal de balayage binaire, ledit contrôleur (206) étant adapté
    pour déterminer un premier tel temps où apparaît une transition générée sous une première condition du lecteur optique (300),
    pour déterminer un second tel temps où apparaît une transition dans un second signal de balayage binaire générée sous une seconde condition du lecteur optique (300), et
    pour comparer le premier temps au second temps afin de détecter une condition de déclenchement.
  15. Lecteur optique (300) selon la revendication 14, dans lequel la source de lumière (310) est une diode à laser.
  16. Lecteur optique (300) selon la revendication 14 ou 15, comprenant en outre une mémoire (210) en communication avec le contrôleur (206) pour mémoriser chaque temps.
  17. Lecteur optique (300) selon l'une quelconque des revendications 14 à 16, comprenant en outre un capteur passif en communication avec le processeur de conditionnement de signal adapté pour détecter un changement de température et actionnant le début des impulsions de la source de lumière (310).
  18. Lecteur optique (300) selon l'une quelconque des revendications 14 à 17, dans lequel le premier temps est dévié pour définir une plage de seuil de déclenchement actuelle.
  19. Lecteur optique (300) selon l'une quelconque des revendications 14 à 18, dans lequel le contrôleur (206) est adapté pour établir un seuil de déclenchement actuel sur la base d'une moyenne d'une pluralité de premiers temps successifs, dans lequel le contrôleur (206) est adapté pour établir une moyenne d'échantillons actuelle sur la base d'une moyenne d'une pluralité de second temps, et dans lequel le contrôleur (206) est adapté pour comparer le seuil de déclenchement actuel à la moyenne d'échantillon actuelle pour déterminer s'il y a suffisamment de changement dans l'énergie de lumière réfléchie indiquant la présence d'un objet.
  20. Lecteur optique (300) selon la revendication 19, dans lequel le contrôleur (206) est adapté pour établir une condition de déclenchement quand l'amplitude de la différence du seuil et de la moyenne d'échantillons actuelle est supérieure à l'amplitude d'un delta configurable.
EP00921892A 1999-06-03 2000-04-06 Declencheur de numeriseur optique mains libres Expired - Lifetime EP1198778B1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
US324794 1989-03-17
US09/324,794 US6357659B1 (en) 1999-06-03 1999-06-03 Hands free optical scanner trigger
PCT/US2000/009360 WO2000075857A1 (fr) 1999-06-03 2000-04-06 Declencheur de numeriseur optique mains libres

Publications (3)

Publication Number Publication Date
EP1198778A1 EP1198778A1 (fr) 2002-04-24
EP1198778A4 EP1198778A4 (fr) 2004-03-31
EP1198778B1 true EP1198778B1 (fr) 2007-01-10

Family

ID=23265130

Family Applications (1)

Application Number Title Priority Date Filing Date
EP00921892A Expired - Lifetime EP1198778B1 (fr) 1999-06-03 2000-04-06 Declencheur de numeriseur optique mains libres

Country Status (4)

Country Link
US (1) US6357659B1 (fr)
EP (1) EP1198778B1 (fr)
DE (1) DE60032904T2 (fr)
WO (1) WO2000075857A1 (fr)

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Also Published As

Publication number Publication date
DE60032904T2 (de) 2007-09-06
EP1198778A1 (fr) 2002-04-24
EP1198778A4 (fr) 2004-03-31
US6357659B1 (en) 2002-03-19
WO2000075857A9 (fr) 2002-04-04
DE60032904D1 (de) 2007-02-22
WO2000075857A1 (fr) 2000-12-14

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